I don’t THINK I agree with your point 1. ie, I favor saying yes to anthropic updates, but I admit that there’s definitely confusing issues here.
Mind expanding on point 3? I think I get what you’re saying, but in general we filter out that part our observations, that is, the fact that observations are occurring at all, Getting that back is the point of anthropic updating. Actually… IIRC, Nick Bostrom’s way of talking about anthropic updates more or less is exactly your point 3 in reverse… ie, near as I can determine and recall, his position explicitly advocates talking about the significance that observations are occurring at all as part of the usual update based on observation. Maybe I’m misremembering though.
Also, separating it out into a single anthropic update and then treating all observations as conditional on your existence or such helps avoid double counting that aspect, right?
Reading the link, the second paper’s abstract, and most of Scott Aaronson’s post, it looks to me like they’re not using anthropic reasoning at all. Robin Hanson summarizes their “entropic principle” (and the abstract and all discussion agree with his summary) as
since observers need entropy gains to function physically, we can estimate the probability that any small spacetime volume contains an observer to be proportional to the entropy gain in that volume.
The problem is that “observer” is not the same as “anthrop-” (human). This principle is just a subtle restatement of either a tautology or known physical law. Because it’s not that “observers need entropy gains”. Rather, observation is entropy gain. To observe something is to increase one’s mutual information with it. But since phase space is conserved, all gains in mutual information must be offset by an increase in entropy.
But since “observers” are simply anything that forms mutual information with something else, it doesn’t mean a conscious observer, let alone a human one. For that, you’d need to go beyond P(entropy gain|observer) to P(consciousness|entropy gain).
(I’m a bit distressed no one else made this point.)
Now, this idea could lead to an insight if you endorsed some neo-animistic view that consciousness is proportional to normalized rate of mutual information increase, and so humans are (as) conscious (as we are) because we’re above some threshold … but again, you’d be using nothing from your existence as such.
The argument was “higher rate of entropy production is correlated with more observers, probably. So we should expect to find ourselves in chunks of reality that have high rates of entropy production”
I guess it wasn’t just observers, but (non reversible) computations
ie, anthropic reasoning was the justification for using the entropy production criteria in the first place. Yes, there is a question of fractions of observers that are conscious, etc… but a universe that can’t support much in the way of observers at all probably can’t support much in the way of conscious observers, while a universe that can support lots of observers can probably support more conscious observers than the other, right?
Now I’m not understanding how your response applies.
My point was: the entropic principle estimates the probability of observers per unit volume by using the entropy per unit volume. But this follows immediately from the second law and conservation of phase space; it’s necessarily true.
To the extent that it assigns a probability to a class that includes us, it does a poor job, because we make up a tiny fraction of the “observers” (appropriately defined) in the universe.
Thanks.
I don’t THINK I agree with your point 1. ie, I favor saying yes to anthropic updates, but I admit that there’s definitely confusing issues here.
Mind expanding on point 3? I think I get what you’re saying, but in general we filter out that part our observations, that is, the fact that observations are occurring at all, Getting that back is the point of anthropic updating. Actually… IIRC, Nick Bostrom’s way of talking about anthropic updates more or less is exactly your point 3 in reverse… ie, near as I can determine and recall, his position explicitly advocates talking about the significance that observations are occurring at all as part of the usual update based on observation. Maybe I’m misremembering though.
Also, separating it out into a single anthropic update and then treating all observations as conditional on your existence or such helps avoid double counting that aspect, right?
Also, here’s another physics example, a bit more recent that was discussed on OB a while back.
Reading the link, the second paper’s abstract, and most of Scott Aaronson’s post, it looks to me like they’re not using anthropic reasoning at all. Robin Hanson summarizes their “entropic principle” (and the abstract and all discussion agree with his summary) as
The problem is that “observer” is not the same as “anthrop-” (human). This principle is just a subtle restatement of either a tautology or known physical law. Because it’s not that “observers need entropy gains”. Rather, observation is entropy gain. To observe something is to increase one’s mutual information with it. But since phase space is conserved, all gains in mutual information must be offset by an increase in entropy.
But since “observers” are simply anything that forms mutual information with something else, it doesn’t mean a conscious observer, let alone a human one. For that, you’d need to go beyond P(entropy gain|observer) to P(consciousness|entropy gain).
(I’m a bit distressed no one else made this point.)
Now, this idea could lead to an insight if you endorsed some neo-animistic view that consciousness is proportional to normalized rate of mutual information increase, and so humans are (as) conscious (as we are) because we’re above some threshold … but again, you’d be using nothing from your existence as such.
The argument was “higher rate of entropy production is correlated with more observers, probably. So we should expect to find ourselves in chunks of reality that have high rates of entropy production”
I guess it wasn’t just observers, but (non reversible) computations
ie, anthropic reasoning was the justification for using the entropy production criteria in the first place. Yes, there is a question of fractions of observers that are conscious, etc… but a universe that can’t support much in the way of observers at all probably can’t support much in the way of conscious observers, while a universe that can support lots of observers can probably support more conscious observers than the other, right?
Or did I misunderstand your point?
Now I’m not understanding how your response applies.
My point was: the entropic principle estimates the probability of observers per unit volume by using the entropy per unit volume. But this follows immediately from the second law and conservation of phase space; it’s necessarily true.
To the extent that it assigns a probability to a class that includes us, it does a poor job, because we make up a tiny fraction of the “observers” (appropriately defined) in the universe.